GH3 2nd Samyang 16mm F2.0, again with problems. What is going on?

S

Stab

Well-known member
Last week I bought the Samyang 16mm F2.0. According to the reviews it is an excellent lens and super sharp at f2.0 throughout the whole frame, except for the far edges. 1 review even says that only the 'last pixels in the corners' are soft at F2.0.


Well, my lens was nothing like that. It its more like the last hundreds of pixels were soft. On top of that, the left side of the screen was much softer than the right side.


I sent it back to the shop and got a new copy today. Went out to do some tests and... Well, the difference between the left side and the right side is improved (not 100%), but its still extremely soft towards the corners of the frame on all sides. Not even that far out of the center... At f8 these problems are pretty much gone, and very much usable at f4 - 5.6, but that's not what I paid this money for... The reviews clearly said sharp at F2.0 throughout the frame.


Well, I might be stupid or crazy, so I want to ask your opinion. The front element of the lens is 'rounded' and that's exactly how the 'sharp plane' looks like in my test shots. Like there is a 'circle of sharpness' in the middle of the screen.


Note that I use the Panasonic GH3 with an adapter (have tried 2 adapters btw). The lens has a Nikon mount. This shouldn't affect this problem, right?
Take a look af the softness on the right and especially left sides.

http://1.static.img-dpreview.com/fi...ums/52429312/1718a517c91a48808bde4047ef4a0952
http://2.static.img-dpreview.com/fi...ums/52429312/9603235538114935b4c28a857767985e
http://4.static.img-dpreview.com/fi...ums/52429312/27ac8a7ec59947fb918b584a2a6b8c12
http://2.static.img-dpreview.com/fi...ums/52429312/426f4bda6ee1415f9c828d2853595359
http://3.static.img-dpreview.com/fi...ums/52429312/a166514a2e0e4284890b69d82b68ce11

All pics are shot at large apertures (f2.0 - f2.2) except for the last one, which was stopped down to f5.6 to correct the problem to show the difference.
Did i get a faulty lens twice? Are the reviews false? Does this lens not work with an adapter? Camera's fault? Or is it just 'normal'?


Hope to hear your opinion. Thank you so much.
 
Quality Control in manufacturing on "bargain" brand lenses is "spotty". No telling what you'll get until you buy.

The Nikon mount should have nothing to do with it, you are obviously experiencing "variations" in manufacture. Again my advice is send it back for a refund. If you don't like to use m4/3 lenses due to the "focus by wire" then search ebay and maybe amazon for Nikon/Nikkor lenses in the focal lengths you want. Generally those will be reasonable sharp and perform well, but even their wide angle optics varied due to lens element centration errors. Wide angle formulae used to be much more complex than telephoto and required more elements with critical element centration.

I went through two 28mm f3.5 Nikkors in the 1970's before the third one tested out sharp enough.

Again, I feel you might be better off (sharpness wise) with the Lumix 14mm f2.5 if you can deal with "focus by wire" (I mostly use autofocus with mine and it does very well). It looks pretty sharp to me wide open.
 
Bruce Foreman said:
Quality Control in manufacturing on "bargain" brand lenses is "spotty". No telling what you'll get until you buy.

The Nikon mount should have nothing to do with it, you are obviously experiencing "variations" in manufacture. Again my advice is send it back for a refund. If you don't like to use m4/3 lenses due to the "focus by wire" then search ebay and maybe amazon for Nikon/Nikkor lenses in the focal lengths you want. Generally those will be reasonable sharp and perform well, but even their wide angle optics varied due to lens element centration errors.

I went through two 28mm f3.5 Nikkors in the 1970's before the third one tested out sharp enough.

Again, I feel you might be better off (sharpness wise) with the Lumix 14mm f2.5 if you can deal with "focus by wire" (I mostly use autofocus with mine and it does very well). It looks pretty sharp to me wide open.
Click to expand...

Thanks Bruce. If it is 100% sure not the fact that it's a Nikon mount lens which is adapted to M43 / the adapter itself, then it must be the lens (again). I also bought the Samyang 35mm 1.4 and the 85mm 1.4 and they are both great lenses. Every lens has some corner softness towards the edges, but they don't have the problem this lens has. I'm happy with them and would really like to have a Samyang 'set' so they look and feel the same.

The reviews state that this 16mm f2.0 is extremely sharp, 'maybe the sharpest APS-C lens on the market'. A good copy of this lens should be amazing, but yea, I'm not getting them :)

I could send the lens back for a 3rd copy, but that seems a bit silly now. I actually had the 14mm 2.5 and sold it. It was fairly sharp, even at f2.5 but I just hated the 'feel' of it. Could barely reach the focus ring with my fingers when there was a ND filter on it. Not ditching the lens though, but I decided to invest in 'large', all manual lenses with good optical quality. The Samyangs ticked those boxes.

I just seem to be unlucky with the 16mm twice in a row now. Or there is something elso going on that I don't know of.
 
Stab said:
The reviews state that this 16mm f2.0 is extremely sharp, 'maybe the sharpest APS-C lens on the market'. A good copy of this lens should be amazing, but yea, I'm not getting them :)
Click to expand...

Before you can really trust reviews you have to have some idea of the experience level of the reviewers and why they are reviewing the gear you're interested in. I "sometimes" put a fair amount of stock in users reviews, but here I'm very carefully assessing how they word what they say and what that tells me about how knowlegeable and professional they are. So far I've been pretty lucky in sorting out the useful from the not so useful reviews.

Samyang is not a brand especially noted for quality, it is "bargain" brand that may be a fair deal for the money. But anytime a reviewer says a "bargain" brand lens is "maybe the sharpest APS-C lens on the market" red flags go up and alarms sound in my head.

When I was stationed on Taiwan working it the unit photo lab with another guy we both bought identical Vivitar 20mm (90 degree field of view) lenses in Nikon mount. Vivitar was a fair quality "bargain" brand in those days (fallen down in quality now). I processed and printed both our work, my lens was quite sharp, his was noticeably softer. I started paying attention to what people were getting in the way of results with Vivitar, Tokina, and the other "bargain" brands. They all seemed to come in 3 grades ranging from quite good to mediocre, and downright abysmal.

I tried the Rokinon 85mm Cine T1.5 for a few weeks, while I wasn't unhappy with it (I had a pretty good sample, pretty sharp and not too much flare), I sold it - gritted my teeth - and paid the price for the Olympus 75mm f1.8. This Oly ran rings around the Rokinon (rebranded Samyang).

Stab said:
I could send the lens back for a 3rd copy, but that seems a bit silly now.
Click to expand...

And you could get an even worse one for the third one.

Stab said:
I actually had the 14mm 2.5 and sold it. It was fairly sharp, even at f2.5 but I just hated the 'feel' of it. Could barely reach the focus ring with my fingers when there was a ND filter on it. Not ditching the lens though, but I decided to invest in 'large', all manual lenses with good optical quality. The Samyangs ticked those boxes.

I just seem to be unlucky with the 16mm twice in a row now. Or there is something elso going on that I don't know of.
Click to expand...

Well, you said the second copy was an improvement over the first. So you could keep it and not worry about the softness in the corners, many viewers might not even notice it. And you could be on the watch for a bargain priced used Lumix 14mm and put up with that when you definitely have to have sharpness from corner to corner. Or "grit your teeth" and pay for the Olympus 12mm f2.0. Most who use that one have nothing but praise for it. I'm kind of watching used prices on amazon on that one.

I don't know how much help I've been, but good luck to you.
 
What brand adapters are you using? Is the problem identical with either adapter?

I wouldnt dismiss that possibility too quickly - it is at least as likely that the problem is there, rather than with the lens itself.
 
Consider testing the lens on a Nikon APC body. That would rule out the adapter & reveal how the lens will perform on a larger sensor in case you ever go that route. It might also give you an idea how it perform on a SpeedBooster.

But as Bruce pointed out, this is a retrofocus wideangle so typically won't perform on par with normal, telephoto, or even a non-retrofocus wide-angle, lenses.

http://en.wikipedia.org/wiki/Angénieux_retrofocus
 
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Indeed. Many elements in the chain, cut some out for test purposes.

Your camera or adapter could be bent/not mounting correct - (by 1/100 of a mm) - such errors show up much worse on wide angle lenses

And of course expectation management. I dont really think any (fast) lenses are too hot wide open, except maybe ones so expensive I have not tried them

S
 
Update:


Went to a shop today and first tried a new copy of the lens. It had the same problem. Then tried a different adapter, the expensive Novoflex adapter.
The problem disappeared and the lens became very sharp at F2.0. No more soft, mushy corners like I had on the pictures.
So it was the adapter after all... I have even used 2 adapters by now. A cheap 'Fotga' adapter and a more expensive 'Kiwi' adapter. Both gave problems with this 16mm wide angle lens.


What do you guys recommend? Bite the bullet on the expensive Novoflex and call it a day? Or are cheaper alternatives like Kipon / Fotodiox likely just as good?
 
The problem with those cheap adapters is that you can't predict what you'll get. I have this Fotodiox adapter and it works well with the Nikon mount Samyang 85mm f/1.4 and the Nikon mount Sigma 28mm f/1.8 on my GH3. But all it means is that my particular copy works with those particular lenses. If I bought it again, I might get a bad copy - there is just no way to predict, as you can see from the reviews. Some people exchange them a few times before they get a good one, some people get a good one on the first try, some never. It's a total crapshoot. I don't have the Novoflex, but I imagine with more expensive adapters there is a more consistent quality and less sample variation, though I've seen complaints from some about the Novoflex adapter too, so it's not a 100% guarantee. For my purposes, I'm happy my Fotodiox works, and for the money it was worth the gamble, but I can understand why you'd be reluctant. Also, remember, an adapter might work with some lenses but not others, even though they're all the same mount (Nikon, or Canon or whatever).
 
Stab said:
Update:


Went to a shop today and first tried a new copy of the lens. It had the same problem. Then tried a different adapter, the expensive Novoflex adapter.
The problem disappeared and the lens became very sharp at F2.0. No more soft, mushy corners like I had on the pictures.
So it was the adapter after all... I have even used 2 adapters by now. A cheap 'Fotga' adapter and a more expensive 'Kiwi' adapter. Both gave problems with this 16mm wide angle lens.


What do you guys recommend? Bite the bullet on the expensive Novoflex and call it a day? Or are cheaper alternatives like Kipon / Fotodiox likely just as good?
Click to expand...
Why are you using an adapter ?
this lens Comes in micro four thirds mount
 
rob12770 said:
Why are you using an adapter ?
this lens Comes in micro four thirds mount
Click to expand...

I bought the Nikon version so I can use it with a Speed Booster which I recently bought. Also, it turned out that the problem was the adapter. With a Novoflex adapter the problem is gone. With the Speed Booster the problem is also gone. This lens does not like el cheapo adapters which are not 100% of the correct size I guess.
 
Stab said:
I bought the Nikon version so I can use it with a Speed Booster which I recently bought. Also, it turned out that the problem was the adapter. With a Novoflex adapter the problem is gone. With the Speed Booster the problem is also gone. This lens does not like el cheapo adapters which are not 100% of the correct size I guess.
Click to expand...
good, im glad you got it sorted out :thumbup:

i recently bought a kiwi FD to MFT adapter but one of the tiny screws fell out.. yep, cheap adapters are no good..
is it a metabones you have ? how is it ?
cheers
 
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